Low back pain is the second most frequently diagnosed pain condition in the United States and even after receiving health care treatment an estimated 40% of patients will experience persistent low back pain. Accurate detection of patients at increased risk for persistent low back pain and the delivery of effective interventions could save the United States billions of dollars each year in health care expenses and lost productivity, and improve quality of life for millions of Americans. Although a precise structural etiology of persistent low back pain is rarely present, recent studies report functional alteration in the peripheral and central nervous system of patients with persistent low back pain that are associated with enhanced pain sensitivity. It has recently been shown that genetic polymorphisms and modifications in gene expression patterns can influence pain sensitivity; however, this has never been studies in patients with low back pain. Therefore, the proposed study will investigate the role of enhanced pain sensitivity on the risk of persistent LBP through characterization of pain sensitivity and pain-sensitivity candidate gene profiling.